Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following? 1. Brakes of mot

1. A. 1, 2, 3 and 5 only
2. B. 1, 2 and 4 only
3. C. 3, 4 and 5 only
4. D. 1, 2, 3, 4 and 5

Answer: D

Explanation

Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge and strongly magnetic behaviour. Airborne magnetite pollution particles < ~200 nm in size can access the brain directly via the olfactory and/or trigeminal nerves, bypassing the blood-brain barrier. These tiny particles, each less than a thousandth the width of a human hair, are generated by a wide variety of processes, both natural and fabricated, including forest fires and wood-burning stoves, road traffic pollution, and many high-temperature industrial processes. In addition to occupational settings (including, for example, exposure to printer toner powders), higher concentrations of magnetite pollution nanoparticles may arise in the indoor environment from open fires or poorly-sealed stoves used for cooking and/or heating, and in the outdoor environment from vehicle (tailpipe and brake wear) and/or industrial PM sources.